High pressure D-tube with enhanced through tube access

ABSTRACT

A high pressure D-tube with enhanced through tube access for use in a well system. The well system includes the tube having an interior and a generally D-shaped exterior surface. An inner support structure spans the interior of the tube. The exterior surface may be formed on a single piece of material. The inner support structure may resist deformation of the tube due to pressure applied to the interior and/or exterior surface of the tube. The inner support structure may form at least a portion of the exterior surface of the tube.

BACKGROUND

The present invention relates generally to operations performed and equipment utilized in conjunction with subterranean wells and, in an embodiment described herein, more particularly provides a high pressure D-tube with enhanced through tube access.

Cross-sectional area in a wellbore is a limited commodity. The wellbore must accommodate equipment and tubing strings passing therethrough, and must provide sufficient flow area for efficient production or injection of fluids therethrough.

In general, where multiple tubing strings are used in a single wellbore, conventional circular cross-section tubing strings have merely been positioned side-by-side in the wellbore. Although this may be the easiest solution, it is also very inefficient in utilizing the available cross-sectional area in the wellbore.

Another solution is to manufacture the tubing strings so that each has a generally D-shaped cross-section. When positioned side-by-side in the wellbore, the two tubing strings together have a generally circular cross-section and occupy a substantial portion of the cross-sectional area of the wellbore, and are therefore able to utilize more of this area for fluid flow, access, etc. Such a tube system is found in the FlexRite™ System marketed by Sperry-Sun Drilling Services.

Although the D-shaped tubes used in the FlexRite™ System represent a significant advance in the art, they do have a few disadvantages. One disadvantage is that the D-shaped tubes are somewhat expensive to manufacture. Another disadvantage is that the D-shaped tubes can have a relatively low burst and collapse strength as compared to a circular tube having equivalent cross-sectional area and wall thickness. Another disadvantage is that the D-shaped tubes have interior corners in which equipment (well tools, wireline, coiled tubing, etc.) conveyed through the tubes can get stuck or bind.

Therefore, it may be seen that improvements are needed in D-shaped tube designs for use in subterranean wells. It is among the objects of the present invention to provide such improvements.

SUMMARY

In carrying out the principles of the present invention, a high pressure D-tube with enhanced through tube access is provided which solves at least one problem in the art. One example is described below in which an inner support structure increases the pressure bearing capabilities of a D-tube. Another example is described below in which an inner support structure provides for enhanced conveyance of tools and equipment through a D-tube.

In one aspect of the invention, a well system includes a tube having an interior and a generally D-shaped exterior surface. An inner support structure spans the interior of the tube.

In another aspect of the invention, the inner support structure may resist deformation of the tube due to external pressure applied to the tube.

In another aspect of the invention, the inner support structure may resist deformation of the tube due to interior pressure applied to the tube.

In another aspect of the invention, the D-shaped exterior surface may be formed on a single piece of material.

In another aspect of the invention, the tube and the inner support structure may be integrally formed from a single piece of material.

In another aspect of the invention, the inner support structure may include a plate.

In another aspect of the invention, the inner support structure may include a tubular structure.

In another aspect of the invention, the inner support structure may include a series of individual support structures distributed longitudinally within the tube.

In another aspect of the invention, the inner support structure may form at least a portion of the exterior surface of the tube.

In another aspect of the invention, the tube may include multiple open-sided sections which are attached to the inner support structure to thereby form the generally D-shaped exterior surface.

These and other features, advantages, benefits and objects of the present invention will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the invention hereinbelow and the accompanying drawings, in which similar elements are indicated in the various figures using the same reference numbers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic partially cross-sectional view of a well system embodying principles of the present invention;

FIG. 2 is an enlarged scale cross-sectional view through a generally D-shaped tube of the well system, taken along line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view of a first alternate configuration of the tube;

FIG. 4 is a cross-sectional view of a second alternate configuration of the tube;

FIG. 5 is a cross-sectional view of a third alternate configuration of the tube;

FIG. 6 is a cross-sectional view of a fourth alternate configuration of the tube;

FIG. 7 is an isometric view of a method of securing a support structure within the fourth alternate configuration of the tube;

FIG. 8 is a cross-sectional view of a fifth alternate configuration of the tube;

FIG. 9 is a cross-sectional view of a sixth alternate configuration of the tube;

FIG. 10 is a cross-sectional view of a seventh alternate configuration of the tube;

FIG. 11 is a side view of a support structure which may be used in tubes embodying principles of the invention;

FIG. 12 is a side view of an alternate configuration of the support structure of FIG. 11;

FIG. 13 is a cross-sectional view of an eighth alternate configuration of the tube; and

FIG. 14 is a cross-sectional view of a support structure used in the eighth alternate configuration of FIG. 13.

DETAILED DESCRIPTION

It is to be understood that the various embodiments of the present invention described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present invention. The embodiments are described merely as examples of useful applications of the principles of the invention, which is not limited to any specific details of these embodiments.

In the following description of the representative embodiments of the invention, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. In general, “above”, “upper”, “upward” and similar terms refer to a direction toward the earth's surface along a wellbore, and “below”, “lower”, “downward” and similar terms refer to a direction away from the earth's surface along the wellbore.

Representatively illustrated in FIG. 1 is a well system 10 which embodies principles of the present invention. The system 10 is similar in many respects to the Isolated Tie-Back System marketed by Sperry-Sun Drilling Services. The system 10 utilizes two tubes 12, 14 having D-shaped cross-sections positioned side-by-side in a parent wellbore 16.

The tubes 12, 14 are run into the wellbore 16 together and are secured to each other at an upper end thereof by a Y-connector 18. Note that each of the tubes 12, 14 could be made up of multiple individual tubes connected to each other in series longitudinally.

A deflector 20 positioned in the wellbore 16 deflects the longer tube 14 from the parent wellbore into a branch wellbore 22 as the tubes are conveyed into the well. The deflector 20 is positioned in the parent wellbore 16 and secured therein by an anchoring device 24, which may be a packer, a latch and inflatable seals, etc.

The tube 14 may have equipment, such as well screens, etc. attached at a lower end thereof. A connector 26 adapts the tube 14 to the generally cylindrical shaped equipment attached therebelow.

The tube 12 is not deflected into the branch wellbore 22, but instead is directed into the deflector 20. Seals 28 in the deflector 20 sealingly engage the tube 12.

With the tube 14 extending into the branch wellbore 22 and the tube 12 received within the deflector 20, an anchoring device 30, such as a liner hanger, is set in the parent wellbore 16. The anchoring device 30 secures the tubes 12, 14 in position and permits commingled flow via the tubes to the parent wellbore above the anchoring device.

Referring additionally now to FIG. 2, an enlarged cross-sectional view of the tube 14 is representatively illustrated, taken along line 2-2 of FIG. 1. The tube 12 which remains in the parent wellbore 16 may be constructed similar to the tube 14 which extends from the parent wellbore into the branch wellbore 22, or they may be differently constructed. For example, the tube 14 could be specially constructed to enhance its ability to flex laterally, so that it may be more easily deflected from the parent wellbore 16 into the branch wellbore 22.

As depicted in FIG. 2, the tube 14 has a generally D-shaped exterior surface 32 on a tubular member 34. In this embodiment, the tubular member 34 is formed from a single piece of material. For example, the tubular member 34 could be extruded so that it initially has the D-shaped exterior surface 32, or the tubular member 34 could initially have a circular or other shape which is later formed (such as, by using a press or roll forming, etc.) into the D-shape, etc. It should be clearly understood that it is not necessary for the D-shaped exterior surface 32 to be formed on a single piece of material, or for the tubular member 34 to be formed in any particular manner, in keeping with the principles of the invention.

An inner support structure 36 spans an interior 38 of the tubular member 34. As illustrated in FIG. 2, the structure 36 is a generally flat plate, but other shapes could be used, if desired. The structure 36 is preferably attached to the tubular member 34 by welding, but other methods (such as bonding, mechanical fasteners, etc.) may be used as well.

The support structure 36 resists deformation of the tubular member 34 due to both external pressure applied to the exterior surface 32, and due to internal pressure applied to the interior 38 of the tubular member. Thus, the support structure 36 enhances both the collapse resistance and burst resistance of the tube 14.

In addition, the support structure 36 divides the interior 38 of the tubular member 34 into separate passages 40, 42. These separate passages 40, 42 may be advantageous in situations where, for example, it is desired to produce fluid (such as hydrocarbons) through one passage while injecting fluid (such as steam, water, treatment chemicals through the other passage, or it is desired to use one passage for access (e.g., for wireline tools, coiled tubing, etc.) and the other passage for fluid flow, etc.

Of course, the separate passages 40, 42 may be used for many other purposes in keeping with the principles of the invention. Furthermore, more than two passages may be provided, for example, by installing multiple support structures 36 in the tubular member 34 and thereby dividing the interior 38 into as many passages as desired.

By using the tubular member 34 as a single piece of material on which the exterior surface 32 is formed, manufacturing costs are decreased to produce the D-shaped exterior. However, it may be difficult in some circumstances to attach the support structure 36 to the interior 38 of the tubular member 34, for example, when it is desired to use the support structure for pressure isolation between the passages 40, 42 and the support structure is to be welded along its entire length to the interior of the tubular member.

In FIG. 3, an alternate construction of the tube 14 (indicated as 14 a) is representatively illustrated in which the support structure 36 may be conveniently attached along its length, since the entire lengths of its longitudinal edges are exposed. Instead of using the tubular member 34, two open-sided sections 44, 46 are attached to either side of the support structure 36.

The sections 44, 46 could be formed by any method, such as pressing, roll forming, etc. For example, the sections 44, 46 could be formed by cutting the tubular member 34 in half longitudinally.

Note that, in the embodiment depicted in FIG. 3, the exterior surface 32 is formed on multiple pieces of material (the sections 44, 46 and the longitudinal edges of the support structure 36). However, the support structure 36 still spans the interior 38, dividing it into the two passages 40, 42, and the support structure still resists deformation of the tube 14 due to internal and external pressure.

Referring additionally now to FIG. 4, the tube 14 is representatively illustrated in another alternate configuration (indicated as 14 b) in which the tube is integrally formed as a single piece of material. For example, the tube 14 could be extruded having the D-shaped external surface 32 and the support structure 36 spanning the interior 38. Alternatively, the tube 14 could be formed by machining it from a single piece of material, or by any other method, in keeping with the principles of the invention.

Referring additionally now to FIG. 5, the tube 14 is representatively illustrated in another alternate configuration (indicated as 14 c) in which the inner support structure is provided as a cylindrically-shaped tubular structure 48 positioned within the interior 38 of the tubular member 34. One advantage of this tube 14 c is that the tubular structure 48 provides an additional longitudinal passage 50 through the tube.

The passage 50 may be pressure isolated from either or both of the other passages 40, 42 in the tube 14 c, or the passage 50 could be in fluid communication with either or both of the passages 40, 42. One advantage of the cylindrical shape of the passage 50 is that it provides a smooth interior for conveying tools, equipment, wireline, coiled tubing, etc. therethrough, without any corners in which such equipment could get caught or bind.

Of course, shapes other than cylindrical may be used for the tubular structure 48. For example, the tubular structure 48 could have an oval or elliptical cross-sectional shape, or any other shape, in keeping with the principles of the invention.

As depicted in FIG. 5, the tubular structure 48 has a relatively thin wall. This provides a large cross-sectional area of the passage 50 for fluid flow and/or access therethrough.

Referring additionally now to FIG. 6, the tube 14 is representatively illustrated in another alternate configuration (indicated as 14 d) in which the inner support structure is still a tubular structure, but the tubular structure (indicated as 48 a) has a relatively thick wall. This thicker wall provides increased internal support for the tubular member 34, to resist deformation due to external and internal pressure applied to the tubular member, while still providing the additional passage 50 for access and flow through the tube 14 d.

To accommodate the increased wall thickness of the tubular structure 48 a without decreasing the cross-sectional area of the passage 50, outer surfaces 52, 54 of the tubular structure may be formed so that they conform to the interior of the tubular member 34. This reduces the wall thickness of the tubular structure 48 a at these areas, but the tubular member 34 outwardly overlies these areas, and the full wall thickness portions of the tubular structure can still resist deformation of the tubular member due to external and internal pressure applied thereto.

Referring additionally now to FIG. 7, an isometric view of the tube 14 d is representatively illustrated. This view gives an enhanced perspective of how the tubular structure 48 a is received within the tubular member 34.

Referring additionally now to FIG. 8, the tube 14 is representatively illustrated in another alternate configuration (indicated as 14 e) with another alternate construction of the tubular structure 48 (indicated as 48 b). In this tube 14 e, the tubular member 34 and the tubular structure 48 b are integrally formed of a single piece of material. For example, the tube 14 e could be extruded, machined from a single piece of material, or formed by any other method.

One advantage of this tube 14 e configuration is that the passage 50 can have an increased cross-sectional area. Another advantage is that the steps of machining the tubular structure 48 b to conform to the interior 38 of the tubular member 34, and attaching the tubular structure to the tubular member are eliminated.

Referring additionally now to FIG. 9, the tube 14 is representatively illustrated in another alternate configuration (indicated as 14 f) in which an alternate configuration of the tubular structure 48 (indicated as 48 c) may be conveniently attached along its length. Instead of using the tubular member 34, two open-sided sections 56, 58 are attached to either side of the tubular structure 48 c.

This alternate construction of the tube 14 f is similar in this respect to the tube 14 a shown in FIG. 3. The sections 56, 58 could be formed by any method, such as pressing, roll forming, etc. For example, the sections 56, 58 could be formed by cutting the tubular member 34 in half longitudinally.

Note that, in the embodiment depicted in FIG. 9, the exterior surface 32 is formed on multiple pieces of material (the sections 56, 58 and outer surfaces of the tubular structure 48 c). However, the tubular structure 48 c still spans the interior 38, provides the additional passage 50, divides the interior into the two passages 40, 42, and the tubular structure still resists deformation of the tube 14 due to internal and external pressure.

Referring additionally now to FIG. 10, the tube 14 is representatively illustrated in another alternate configuration (indicated as 14 g) in which an alternate configuration of the tubular member 34 (indicated as 34 a) is used. In this tube 14 g, interior surfaces 60, 62 of the tubular member 34 a are shaped to conform to the cylindrical exterior of the tubular structure 48 d. One advantage of this tube 14 g alternate configuration is that the inner support provided by the tubular structure 48 d is not compromised at all by removing any of its wall thickness, and the passage 50 can still have a relatively large cross-sectional area.

Referring additionally now to FIG. 11, the tubular structure 48 is representatively illustrated in an alternate configuration (indicated as 48 e) from an elevational view. In this view it may be seen that slots 64 are cut through the tubular structure 48 e on opposing lateral sides.

These slots 64 allow the tubular structure 48 e to more easily flex, thereby allowing the tube 14 to more easily flex when it is deflected from the parent wellbore 16 into the branch wellbore 22 as depicted in FIG. 1. Accordingly, the slots 64 are preferably positioned in the lateral sides of the tubular structure 48 e which would experience tension and compression when the tube 14 is flexed or laterally deflected.

The alternate configuration of the tubular structure 48 e may be used in place of the tubular structure 48 of FIG. 5, the tubular structure 48 a of FIG. 6 (in which case the outer surfaces 52, 54 would be formed on the lateral sides of the tubular structure 48 e having the slots 64 therein), and the tubular structure 48 d of FIG. 10. Of course, the tubular structure 48 e could be used in other alternate configurations of the tube 14 in keeping with the principles of the invention.

Referring additionally now to FIG. 12, the tubular structure 48 is representatively illustrated in another alternate configuration (indicated as 48 f). This configuration is similar to that depicted in FIG. 12, except that the slots 64 are offset on the opposite lateral sides of the tubular structure 48. One advantage of this configuration is that it may provide an increased tensile strength for the tubular structure 48 f, while still providing a reduced resistance to lateral flexing.

Referring additionally now to FIG. 13, the tube 14 is representatively illustrated in another alternate configuration (indicated as 14 h) in which the tubular structure 48 has an alternate configuration (indicated as 48 g). The alternate configuration tube 14 h is represented as a cross-sectional view of the tube 14 c, taken along line 13-13 of FIG. 5.

In this alternate configuration tube 14 h, increased flexibility is provided by having a series of multiple tubular structures 48 g distributed longitudinally within the tubular member 34. The tubular structures 48 g overlap each other (e.g., each tubular member has a male end and a female end), so that the passage 50 is continuous through the multiple tubular structures. Alternatively, the tubular structures 48 g could be individual longitudinally spaced apart rings which do not overlap each other.

One way of attaching the individual tubular structures 48 g to the tubular member 34 would be to provide a series of slots 66 through the tubular member, and weld the tubular structures to the tubular member in the slots. Of course, other methods of attaching the tubular structures 48 g to the tubular member 34 could be used (such as adhesive bonding, mechanical fasteners, etc.) in keeping with the principles of the invention.

Referring additionally now to FIG. 14, the tubular structures 48 g are depicted apart from the tubular member 34, and the tubular structures are shown being laterally flexed or bent. In this view the manner in which the tubular structures 48 g are readily flexed while maintaining the continuous passage 50 may be seen. Note that seals (such as orings, etc.) could be provided where the tubular structures 48 g overlap each other, so that the passage 50 could be pressure isolated from the other passages 40, 42, if desired.

The tubular structures 48 g may be used in place of the tubular structure 48 of FIG. 5, the tubular structure 48 a of FIG. 6 (in which case the outer surfaces 52, 54 would be formed on opposite lateral sides of the tubular structures 48 g), the tubular structure 48 d of FIG. 10 and the tubular structures 48 e, 48 f of FIGS. 11 & 12. Of course, the tubular structures 48 g could be used in other alternate configurations of the tube 14 in keeping with the principles of the invention.

Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the invention, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to these specific embodiments, and such changes are within the scope of the principles of the present invention. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents. 

1. A well system, comprising: a tube having an interior and a generally D-shaped exterior surface; and an inner support structure spanning the interior of the tube.
 2. The well system of claim 1, wherein the inner support structure resists deformation of the tube due to exterior pressure applied to the tube.
 3. The well system of claim 1, wherein the inner support structure resists deformation of the tube due to interior pressure applied to the tube.
 4. The well system of claim 1, wherein the D-shaped exterior surface is formed on a single piece of material.
 5. The well system of claim 1, wherein the tube and the inner support structure are integrally formed from a single piece of material.
 6. The well system of claim 1, wherein the inner support structure comprises a plate.
 7. The well system of claim 1, wherein the inner support structure comprises a tubular structure.
 8. The well system of claim 1, wherein the inner support structure comprises a series of individual support structures distributed longitudinally within the tube.
 9. The well system of claim 1, wherein the inner support structure forms at least a portion of the exterior surface of the tube.
 10. The well system of claim 1, wherein the tube comprises multiple open-sided sections which are attached to the inner support structure to thereby form the generally D-shaped exterior surface.
 11. A well system, comprising: a tube having an interior and a generally D-shaped exterior surface, the exterior surface being formed on a single piece of material; and an inner support structure within the interior of the tube, the support structure resisting deformation of the tube due to pressure applied to the exterior surface.
 12. The well system of claim 11, wherein the tube and the inner support structure are integrally formed from a single piece of material.
 13. The well system of claim 11, wherein the inner support structure comprises a plate.
 14. The well system of claim 11, wherein the inner support structure comprises a tubular structure.
 15. The well system of claim 11, wherein the inner support structure comprises a series of individual support structures distributed longitudinally within the tube.
 16. The well system of claim 11, wherein the inner support structure resists deformation of the tube due to interior pressure applied to the tube.
 17. A well system, comprising: a tube having an interior and a generally D-shaped exterior surface; and an inner support structure resisting deformation of the tube due to pressure applied to the exterior surface, and the inner support structure forming at least a portion of the exterior surface of the tube.
 18. The well system of claim 17, wherein the tube comprises multiple open-sided sections which are attached to the inner support structure to thereby form the generally D-shaped exterior surface.
 19. The well system of claim 17, wherein the inner support structure comprises a plate.
 20. The well system of claim 17, wherein the inner support structure comprises a tubular structure.
 21. The well system of claim 17, wherein the inner support structure resists deformation of the tube due to pressure applied to the interior of the tube. 